The need for technology for forming a fine pattern is increased with the progress of integration of semiconductor devices. As a technology for coping with the miniaturization of patterns, a pattern formation method utilizing the microphase separation of a self-assembling material is drawing attention. In microfabrication technology, it is necessary to arrange separated phases into a prescribed arrangement with a guide pattern as a reference. To form a pattern by utilizing the microphase separation of a self-assembling material, it is important to phase-separate the self-assembling material with good accuracy.